Causes and symptoms

Cold sores are caused by the Herpes Simplex Virus (HSV), an infection that the majority of Canadians contract during childhood or adolescence. “It’s the most common of viruses and can affect individuals of any age,” explains Dermatologist, Dr. Gary Sibbald. “The first infection often occurs before the age of 14, and up to 70 percent of the population have had a past infection.”

HSV is highly transmittable and primarily passed on via intimate oral contact with an active cold sore, sharing kitchen utensils or asymptomatic shedding of the virus between acute episodes. People who suffer with recurrent cold sore eruptions will normally experience between one and six outbreaks per year.

Regular recurrences of a cold sore will have less severe symptoms than a primary outbreak, which can include a period of fever, oral ulcerations, and gingivitis. Intermittent cold sore eruptions, also known as recurrent herpes labialis, are characterized by the appearance of small blisters on the lip, which usually last for between one and two weeks.

It is known that frequent recurrences are associated with a significant negative impact on quality of life. “There’s a common negative view that a cold sore is something dirty, something bad,” says Dr. Sibbald. “That view stops people from talking to others about it or disclosing it to friends and sexual partners.”

Six million Canadians are affected; proper treatment and control exists.


Although it may seem impossible to avoid contracting HSV in the first place, realizing what triggers cause possible outbreaks, and then doing whatever you can to avoid them is essential. Although in some cases, triggers are simply unavoidable. Cold sore triggers include: fever, sun exposure, other existing viral respiratory infections, emotional stress, fatigue, trauma, iron deficiency, oral cancer therapy, immune-suppressing chemotherapy for cancer, oral and facial surgery, gastrointestinal upset, and menstruation. “UV rays are the number one trigger of cold sores,” says Dr. Sibbald.


There is a common misconception that cold sores cannot be properly treated and controlled. It’s also damaging for people affected, who may be reluctant to seek treatment if they take on this false information as truth.

Most patients prefer a cream that is applied directly on the cold sore lesion area (a topical treatment).

Xerese is a new topical treatment that has been shown to shutdown the development of cold sores and prevent cold sore progression. It decreases the size of the lesion and speeds up healing time. Patients are recommended to apply Xerese five times a day for five days at the first sign of burning and stinging.

“Xerese is a combination of acyclovir and hydrocortisone,” says Dr Sibbald. “The acyclovir stops the viral replication and the hydrocortisone’s anti-inflammatory action accelerates the recovery stage. It may even prevent the redness at the early stages of the sore from ever occurring.”

Valtrex is an oral treatment also shown to shut down the development of a cold sore. Patients are recommended to take four pills at the first sign of burning and then another four between four and 12 hours later. “It works by interfering with the enzyme that’s important for viral replication,” says Dr. Sibbald “It’s one of the safest drugs that we’ve got.”

If you’re one of the six million Canadians that is affected by cold sores, make sure that you visit your doctor to discuss treatment options.